On 11/1/26 3:09 AM, khaliforce wrote:
Hi Marek, Tom,
I retested v2 on MangoPi MQ Pro using the downstream D1 port
based on U-Boot v2026.10.
The boot path was U-Boot -> GRUB EFI -> Linux 7.3.1.
Two USB hubs were cascaded, with one flash drive on each hub:
- Near: 64GB Samsung Flash Drive FIT, attached to the first hub.
- Far: 8GB USB Flash Disk, attached to the second hub.
I added temporary port-path and device-identity traces.
I matched the serial numbers against Linux to confirm each drive.
No manual "usb stop" command was used.
Relevant excerpts follow, with intermediate lines omitted:
USBTRACE identity path=usb@4200000/0/1/2/3 vid=090c pid=1000
serial=5610050000154305 product="USB Flash Disk"
USBTRACE done path=usb@4200000/0/1/2/3 driver=usb_mass_storage
flags=4000 active=0
USBTRACE done path=usb@4200000/0/1/2 driver=usb_hub flags=4000 active=0
USBTRACE identity path=usb@4200000/0/1/3 vid=090c pid=1000
serial=0352315070000417 product="Flash Drive FIT"
USBTRACE done path=usb@4200000/0/1/3 driver=usb_mass_storage flags=4000 active=0
USBTRACE done path=usb@4200000/0/1 driver=usb_hub flags=4000 active=0
USBTRACE done path=usb@4200000/0 driver=usb_hub flags=4000 active=0
USBTRACE ehci_deregister dev=usb@4200000 ret=0
USBTRACE done path=usb@4200000 driver=ehci_generic flags=4600 active=0
USBTRACE ohci_deregister dev=usb@4200400 ret=0
The farther drive was removed before the nearer drive.
Children were removed before their parent hubs and the EHCI controller.
Linux booted successfully, detected both drives, and reported
no failed services.
Both drives used EHCI. OHCI had no external devices.
I lack suitable hardware to test downstream device removal through OHCI.
That resolves my concern. Thank you for testing.
